1. Field of the Invention
The present invention concerns magnetoresistive sensors, i.e. sensors which make use of the variation in resistivity of the sensor material as a function of the variation of a magnetic field.
2. Description of the Prior Art
At present, sensors using the magnetoresistive effect are used in various systems for reading magnetic recordings. These sensors are made of a ferromagnetic alloy with high magnetoresistance which is placed in the magnetic circuit of a read head. In this case, variations of the electrical resistance of the sensor are detected as the tape passes. The highly magnetoresistive alloys used at present are generally nickel-based ferromagnetic alloys, such as Ni.sub.80 Fe.sub.20 type alloys or Ni Co alloys for which the magnetoresistance at room temperature corresponds to a resistance variation of a few percent.
One of the main disadvantages of these sensors is their noise. These alloys are not monocrystalline and they have numerous magnetic domains for the magnetic fields corresponding to the functioning point of the sensor. These numerous magnetic domains are the main cause of noise.
The aim of the present invention is to remedy these disadvantages by proposing a new structure for the sensitive element of magnetoresistive sensors.